a-a a-b aaa aab aad aaf aak aan aao aas ab- aba abb abd abf abk abn abo abs ad- ada adb add adf adk adn ado ads af- afa afb afd aff afk afn afo afs aka akb akd akk akn ako aks an- ana anb and anf ank ann ano ans aoa aob aod aof aok aon aoo aos as- asa asb asd asf ask asn aso ass baa bab bad baf bak ban bao bas bba bbb bbd bbf bbk bbn bbo bbs bda bdb bdd bdf bdk bdo bds bfa bfb bfd bff bfn bfo bfs bka bkb bkf bkk bkn bko bks bna bnb bnd bnf bnk bnn bno bns boa bob bod bof bok bon boo bos bsa bsb bsd bsf bsk bsn bso bss daa dab dad daf dak dan dao das dba dbb dbd dbf dbk dbn dbo dbs dda ddb ddd ddf ddk ddn ddo dds dfa dfb dfd dff dfk dfn dfo dfs dka dkb dkk dko dks dna dnb dnd dnf dnk dnn dno dns doa dob dod dof dok don doo dos dsa dsb dsd dsf dsk dsn dso dss faa fab fad faf fak fan fao fas fba fbb fbd fbf fbk fbn fbo fbs fda fdb fdd fdf fdk fdn fdo fds ffa ffd fff ffk ffn ffo ffs fka fkb fkf fkk fna fnb fnd fnf fnk fnn fns foa fob fof fok fon foo fos fsa fsb fsd fsf fsk fsn fso fss ka- kaa kab kad kaf kak kan kao kas kba kbb kbd kbf kbk kbn kbo kbs kda kdb kdf kdk kdo kds kfa kfd kff kfo kfs kkb kkk kkn kks kn- kna knd knf knk knn kno koa kob kod kof kok kon koo kos ksa ksb ksd ksf ksk ksn kso kss naa nab nad naf nak nan nao nas nba nbb nbd nbf nbk nbn nbo nbs nda ndb ndd ndf ndk ndn ndo nds nfa nfb nfd nff nfk nfn nfo nfs nka nkf nkk nkn nko nks nna nnb nnf nnk nnn nno nns no- noa nob nod nof nok non noo nos nsa nsb nsd nsf nsk nsn nso nss oaa oab oad oaf oak oan oao oas ob- oba obb obd obf obk obn obo obs oda odb odd odf odn odo ods of- ofa ofb ofd off ofn ofo ofs oka okb okd okk oko oks on- ona onb ond onf onk onn ono ons oo- ooa oob ood oof ook oon ooo oos os- osa osb osd osf osk osn oso oss saa sab sad saf sak san sao sas sba sbb sbd sbf sbk sbn sbo sbs sda sdb sdd sdf sdk sdn sdo sds sfa sfb sfd sff sfk sfn sfo sfs sk- ska skb skd skf skk sko sks sna snb snd snf snk snn sno sns soa sob sod sof sok son soo sos ss- ssa ssb ssd ssf ssk ssn sso sss